The goal of this two-year R34 treatment development grant is to develop a mobile health (mHealth) application that will both advance theory in and clinical practice of homework (HW) implementation. HW can be described as between-session exercises where the client practices specific skills learned within-session in order to promote skill acquisition, which ultimately leads to improved acute- as well as longer-term therapeutic benefits on targeted outcomes, generalization of treatment effects and maintenance of treatment gains. Despite data demonstrating that HW is critical to achieving maximal benefits from evidence-based treatments, very little theory-driven approaches have been conducted focusing on improving the HW process. Through utilizing self- determination theory as a guiding framework and integrating principles from the field of gamification and goal-setting, the aim is to develop a two-component mHealth HW application (My MFG). The first component focuses on delivering HW via a highly engaging, multiplayer, interactive, cooperative, and skill-building game platform aimed at improving the Design and Do process of HW. The second component focuses on targeting factors putatively related to poor HW implementation within the Do process. The process of the development of My MFG will be guided by the clinic and community development model and iterative software development process to maximize the feasibility and sustainability of My MFG within practice settings often characterized by limited resources. Findings from this study have broad implications for evidence-based treatments for youth and adult mental health disorders that emphasize HW as the link between treatment and improvements in targeted outcomes.